Hydrochlorofluorocarbon HCFC-133a (CF3CH2Cl) is an anthropogenic compound whose
consumption for emissive use is restricted under the Montreal Protocol. A recent study showed rapidly
increasing atmospheric abundances and emissions. We report that, following this rise, the atmospheric
abundance and emissions have declined sharply in the past three years. We find a Northern Hemisphere
HCFC-133a increase from 0.13 ppt (dry-air mole fraction in parts per trillion) in 2000 to 0.50 ppt in
2012-mid-2013 followed by an abrupt drop to ∼0.44 ppt by early 2015. Global emissions derived from these
observations peaked at 3.1 kt in 2011, followed by a rapid decline of ∼0.5 kt yr-2 to reach 1.5 kt yr-1 in 2014.
Sporadic HCFC-133a pollution events are detected in Europe from our high-resolution HCFC-133a records at three European stations, and in Asia from samples collected in Taiwan. European emissions are estimated to
be <0.1 kt yr-1 although emission hot spots were identified in France.